The present invention relates to personal mobile computing devices commonly known as mobile devices. More particularly, the present invention relates to a system and method for delivering information to, and programming mobile devices.
Mobile devices are small electronic computing devices often referred to as personal digital assistants. Many such mobile devices are pagers, hand held devices, or palm size devices, which comfortably fit within the hand. One commercially available device is sold under the tradename HandHeld PC (or H/PC) having software provided by Microsoft Corporation of Redmond, Washington.
Generally, the mobile device includes a processor, random access memory (RAM) , and an input device such as a keyboard and a display. The keyboard can be integrated with the display, such as when the keyboard is incorporated as a touch sensitive display. A communication interface is optionally provided and is commonly used to communicate with the desktop computer. A replaceable or rechargeable battery powers the mobile device. Optionally, the mobile device can receive power from an external power source that overrides or recharges the built-in battery.
In some prior applications, the mobile device is used in conjunction with the desktop computer. For example, the user of the mobile device may also have access to, and use, a desktop computer at work or at home or both. If the mobile device is an H/PC brand device or other similar device, the user typically runs the same types of applications on both the desktop computer and on the mobile device. Thus, it is quite advantageous for such mobile devices to be designed to be coupled to the desktop computer to exchange information with, and share information with, the desktop computer.
Another technique for providing information to mobile devices is through a wireless transmission link. Such information can include electronic mail or news, weather, sports, traffic and local event information. The information is typically obtained from a desktop computer connected to the Internet and delivered over a wired connection. However, it may be desirable to deliver such information over a wireless connection as well. A wireless receiver on the mobile device can act to receive information as it is being sent to the mobile device.
Where the mobile device is a pager, each pager in a given system has one or more addresses. When a message is transmitted over a wireless channel, it is destined for an address. All pagers assigned to that wireless channel receive the message and check the address contained in the message against its own addresses. This address-matching algorithm can be implemented either in the hardware, or in software, or in a combination of hardware and software. If the address associated with the incoming message does not match any of the addresses on the pager, then the message is discarded. However, if the address does match one of the addresses on the pager, then the message is accepted and forwarded to higher level software in the protocol stack on the pager for suitable processing.
Addresses can typically be of two types. The first is a personal address which is unique within a given wireless network (i.e., only one pager has that address). The personal address is used for sending a message to a particular pager.
The second type of address is a broadcast address. A broadcast address is typically programmed into many pagers within a given wireless network. Thus, a single message delivered over a broadcast address is received and accepted by multiple pagers in the network. Such addresses are used for implementing broadcast services, such as the news, traffic, weather, etc. services mentioned above.
There is currently no convenient way to reprogram the addresses in mobile devices, such as pagers. Instead, the pagers must be brought back to a service center where special tools are used to access and modify the internal storage of the pager, where the addresses are stored. Some prior systems have attempted to accomplish over-the-air programming. In such systems, the network owner (or carrier) sends a special message to the pager that changes the addresses in the pager.
However, to date, this has been quite uncommon. Over-the-air programming presents significant difficulties with respect to security. In other words, if the provider of the broadcast services being programmed wishes to charge users a fee or subscription price to receive the broadcast services, then the programming messages must be highly secure. Otherwise, unauthorized programming of the pager devices to receive the broadcast services would be problematic.
Encryption techniques have not been used in any effective way in the paging environment. There are a number of reasons for this. First, processors in conventional pagers are typically not provided with any means to implement decryption algorithms in such a way as to decrypt encrypted messages arriving at the pager. In addition, there is currently no method of allowing a secure element (such as a device driver) to rely on an external software security element (such as a security component dynamically linked library (DLL)) to perform decryption. In order to decrypt the content of an encrypted message, the security component must obtain from the device driver the appropriate decryption key. Thus, the device driver (which may be assumed to be a trusted device) must pass the encryption key to an external element (the security component DLL), which compromises the security of the encryption key, and thus the security of the subscription system.
Further, with the advent of global computer networks, such as the Internet, information broadcast services have become prevalent and important. However, a typical pager can only have a limited number of addresses (usually 2-8). A much larger number of broadcast services would desirably be offered to suit a wide range of interests and needs for the various users of the pagers. That being the case, each individual user would need to have the pager reprogrammed (by taking it back to a service center) so that it contained the addresses which would select desired broadcast services, desired by the individual user. This would need to be done each time the user wished to add, delete, or change the broadcast services selection. This is highly cost inefficient and is believed to have at least stunted the growth and proliferation of such broadcast services.
For these reasons, many paging carriers provide free broadcast services. These items are free because there is no current cost effective way to manage subscriptions to these services. The content of these services is provided by an independent content provider but is transmitted by wireless network operators. If a user wishes to add a new service, or drop a service, the device must be returned to the wireless network operator service center for reprogramming of addresses contained in the pager. This means that the independent content provider cannot manage subscriptions independent of the carriers (or wireless network operators). Even if this were to be accomplished, as discussed above, there is currently no efficient mechanism by which content messages could be transmitted in a secure fashion.
A system controls access to broadcast messages received by a plurality of mobile devices. Selected mobile devices are provided with a broadcast encryption key (BEK). The broadcast messages are encrypted using the BEK prior to broadcasting so that the selected mobile devices containing the BEK can decrypt the broadcast messages. The broadcast messages are then broadcast.